h.a.r.s. journal · came into place. there are currently about 75,000 licensed users in the uk....

H.A.R.S. JournalJournal of the Hereford Amateur Radio Society Issue No 24 • July 2020

H.A.R.S. Journal Issue No 24 • July 2020 Page �

Chairman: NigelHancocksG4XTF•Treasurer:BenElms‑LesterM0SWV•Secretary:DuncanJamesM0OTGCommittee: DavePorterG4OYX,DaveButlerG4ASRContestCaptain,MikeBushG3LZM,TimBridgland‑TaylorG0JWJ,

GeoffWilkersonG8BPN,AdrianHartlandG8IVO,RichardWebbM0RPW,TristanQuineyM0VXX

Editorial

Hello ladies and gentlemen

First of all I do hope everyone is safe during these largely unpredictable times. The radio operating rooms have been a wonderful “port” for we radio amateurs to reach out to each other and to offer support where needed.

May I please apologise for the delay in presenting this issue – it was mainly due to my computer problems …but everything OK now.

In this Journal we have a wonderful article by Bob Bowden (G3IXZ) relating to Hereford’s first radio amateur Walter Pritchard (2QO) who was operating wireless equipment prior to WW1.

There are a number of constructional articles within which we might choose to ponder over, articles which might cause us to switch on our workshop facilities and produce…a kind of lock-down relief.

If you have any news or article ideas for the next issue, please do pass them on to me.

73 es gud DX Mike G3LZM (Ed)

Hereford Amateur Radio

Society

Hi Folks,

Matt G8XYJ would like to let you all know that in order to include as many Club members as possible the 2m net on Wednesday evenings at 8pm will now alternate between the Hereford repeater GB3ZA (today �0th June), and the Woofferton repeater GB3VM (17th June) hosted by Matt G8XYJ, Josh M0WYP & Tony M0VDO using the Club callsign G6YDD.

The 80m net on Saturday mornings at 9.30 am on 3.77MHz. will continue, using the callsign G3YDD with Net Controller, Tony, M0VDO.

It’s a sure way to beat the lock-down blues so give them a call.

73 and take care Duncan James (M0OTG) HARS Hon. Sec.

[email protected]

Note - GB3ZA - Hereford Repeater

Frequency 145.7375 MHz

Offset -0.6 MHz Tone 118.8

Issue No 24 • July 2020 H.A.R.S. Journal

VHF Contest Calendar 2020

H.A.R.S. Journal Issue No 24 • July 2020

Coronavirus: How amateur

radio is connecting people

during lockdown

By Vanessa Pearce BBC News

Image copyright Pete Sipple

The Sipple family - Pete, Sarah and Kathryn - say they’ve seen a “massive” spike in interest for online

courses

Amateur radio use in the UK has seen a “significant” rise during the coronavirus lockdown as people seek new ways of staying connected. The national body that represents users - the Radio Society of Great Britain (RSGB) - has said many people who formerly enjoyed the hobby are also returning to it.

Mark Rider’s social life before the coronavirus lockdown consisted of the occasional trip to the pub, rehearsing with musician friends and visiting his wife in her care home.

“But when I knew that wasn’t going to happen any time soon I decided to dust off my amateur radio equipment to seek out some other social interaction,” he says.

Mr Rider, a retired engineer from North Warwickshire, said “ragchewing” - or chatting to people on the airwaves - “has become one of the highlights of my day”.

“Because I live on my own, and because of lockdown, I knew I couldn’t do what I used to do, which wasn’t going to be very good for me or my mental health.”

Image copyright Mark Rider

Mark Rider: “Just speaking to somebody else in the same situation is very rewarding”

The 67-year-old says keeping in touch with others has been more important since his wife was taken into care after a stroke.

“Just speaking to somebody else in the same situation is very rewarding,” he says.

The RSGB defines amateur radio as a “technical hobby for people who want to learn about, use and experiment with wireless communications”, like Mr Rider, who uses his radio kit to speak to others using designated radio frequencies.

Steve Thomas, RSGB general manager, says the organisation has experienced a threefold increase in the number of people asking to sit licensing exams since social distancing rules came into place. There are currently about 75,000 licensed users in the UK.

“Across the country, clubs and individual radio amateurs are supporting one another by setting up ‘nets’, or online meetings,” Mr Thomas says.

Image copyright Bill Rowland

Anne-Marie Rowland has been holding twice-weekly meetings to support her community


Anne-Marie Rowland has been running twice-weekly meetings to help keep people in contact.

The ��-year-old from Leedstown near Hayle in Cornwall, who has held a licence for about a year, set up the transmissions with the Cornish Amateur Radio Club to help keep people in contact during lockdown.

“We have some regulars but also some new people join in,” she says.

Dad Bill, who also runs a weekly meeting, says “we’re always available with the radio on, there are a lot of older people out there self-isolating, so this helps them feel connected”.

Amateur radio users have also been showing their support for the NHS by adding “/NHS” as an extension to their call signs and taking part in a “get on the air to care” campaign (#GOTA2C), aimed at supporting the emotional health and wellbeing of the radio communications community.

An amateur radio call sign, issued by the Government Office for Communication (Ofcom), is a series of letters and numbers unique to each radio operator and allows enthusiasts to identify each other and establish which country they are in.

Image copyright Paul Devlin

The NHS radio station GB1NHS attracts “queues” of people wanting to engage, says Paul Devlin

Paul Devlin, from the NHS Emergency Care Improvement Support Team, launched the campaign in an “unprecedented” partnership with the RSGB, whose National Radio Centre is based at Bletchley Park in Milton Keynes.

He was responsible for creating the health service’s amateur radio station GB�NHS.

“The NHS is the only government level organisation to routinely use amateur radio to help improve the lives of communities globally,” he explains.

“We want radio operators to simply get on the air, reach out to fellow enthusiasts and check how they’re doing,” says the 55-year-old from Lichfield, Staffordshire.

“Being such a well-recognised brand, whenever GB�NHS is on the air we have queues of radio operators wanting to engage with our messages.”

Image copyright NHS

Amateur radio users are being urged to “get on air to care”

Analysis by Jim Lee, BBC Radio announcer and newsreader

I first got hooked by the magic of radio as a schoolboy in Nuneaton. I passed the necessary technical exam and Morse test and got my call sign (G4AEH) dangerously close to my A-Level exams.

Listening to the pirate stations in the 60s made me want to work in radio. When most of them were closed down, tuning around the shortwave bands on a radio that my mum bought for me at a church jumble sale led me to amateur radio.

That was over 50 years ago and even though I spend a lot of time reading the news and introducing programmes for the BBC, communicating around the world with an antenna I’ve made from a few bits of wire is still part of radio’s magic.

Amateur radio is ideal for social distancing and it’s no surprise that more and more people are turning to it during this crisis. Social media and video calls are OK, but depend on there


being sufficient internet bandwidth for efficient communication.

You can’t FaceTime the International Space Station, but there have been occasions when radio amateurs have been able to speak to the astronauts via their radio sets in a shed or back bedroom.

The digital world and amateur radio can exist side by side. There’s no way the new kid on the block will replace the magic of talking to someone on the other side of the world with less power than it takes to run a light-bulb. It’s science in action.

Image copyright Pete Sipple

Sarah Sipple helps run the Essex Ham club with husband Pete

The RSGB introduced remote invigilation in the middle of April to allow people to take their foundation exam - the entry step to obtaining an amateur radio licence.

Pete Sipple, 50, from Leigh-on-Sea, who runs the Essex Ham amateur radio club with his wife Sarah, has been offering online training courses for the exam for some time but says since the coronavirus lockdown he’s seen a “massive” surge in demand.

“We’ve had 1,135 people apply for a course so far this year, and due to the Covid demand, are running two courses a month instead of one,” he says.

Mrs Sipple, 46, says she’s noticed a rise in transmissions from people who haven’t been on air very recently.

“Pete has been getting messages saying, ‘I haven’t used the radio for six or seven years, can you just help me get back into it?’”

Image copyright Callum McCormick

Callum McCormick was able to mobilise help for a man “down to his last half cup of milk”

Callum McCormick, a 6�-year-old antenna manufacturer, hosts a daily amateur radio welfare “net” for the over-65s from his home in Lapworth, Warwickshire. It has reached hundreds of users, with thousands more watching via his YouTube channel.

“The oldest user who has been in touch is �0�-year-old George from Dorchester who just wanted to call and tell us he and his wife Ivy were being looked after by their daughter and were OK.”

Mr McCormick says he was able to help one disabled and housebound user “who was down to his last half cup of milk”.

“He’d been calling in and over the days I’d clocked he needed help, so I managed to mobilise a response to get some shopping to him and he’s now being looked after by the council,” Mr McCormick says.

“I wanted to do something for the old boys who were feeling a little bit lost and isolated.”

https://www.bbc.co.uk/news/uk-england-52442553

Thanks, Callum … Mike G3LZM (Ed.)




Coaxial fed Windom Antenna

The Windom is an Off-center wire multiband Antenna. The old version was fed just by a single-wire connected on �/3 of antenna’s overall length or with an open-line feeder (later versions). Here is another model with coaxial feeder, which is compatible with Solid States - 50 Ohm output transceivers.

Fig.1

The page describes a Windom antenna with a 4:� homebrew transformer. The feed-point of this type of antenna (off center) has an impedance of about 300 Ohms. With a 4:1 Balun transformer is possible to feed easily by using a coaxial cable of 75 Ohms (300/4=75), like RG59 or RG��. In practice, under this condition we have an SWR ratio of 1:1,5, but that is no problem if your transceiver has an internal Antenna Tuner. The SWR 1:1,5 it can be easily minimized by using the antenna tuner.

The antenna works on all bands between 3.5 - 28 MHZ including WARC bands other than �0.� MHZ. The accepted power with this balun is 300 W and the SWR is quite low, not more than 2:� at the band edges. FIG. 2 shows the Balun transformer.

The wire is a simple electrical-wire � - 1,5 mm2.(Double “Red-Black” wire for LoudSpeakers)

9-�0 turns on ferrite rod is enough but keep in mind before winding: “cut” the two cables (red & black on my picture above) with an equal length.

Fig.2

The “B” point of balun is being connected with “L�” part of antenna and the “A” point with “L2” (see FIG.�).

This aerial can be manufactured in two versions:


1) Full size with an overall length (L) of 41 m. In this case the “L1” is 27.5 m and the “L2” is �3.5 m.

2) Half size with an overall length of 20.5 meters. L1= 13.75 & L2 = 6.75 m

ATTENTION: the small version works only for �0, 20 & 40 meter Bands.

Actually, this antenna is a compromise but in practice works very well! On the other hand, it is a simple-wire multiband antenna, it can be manufactured very easily by anyone and that is a great advantage. I have on my QTH the small version for a couple of years and the results are very good. On 40 m band the antenna is about -6 Db (1 S) lower of a full size dipole but in practice it has the same behavior on locals and DX stations. On 20 meter Band the antenna is excellent. The multi lobe radiation pattern of antennas giving excellent results and its much - much better than a dipole. I have thousands of QSOs on 20 m band by using this antenna and almost 4.000 QSOs with State-side stations on CW, just by using an output power of about 150 Watts.

The behavior of this antenna on �0 m. Band is a “mystery” for me! Some times is excellent with DX stations but some other times its like a “Dummy load”! Probably, because the antenna is two-lamda has a very complicated radiation pattern on this band, with several “shadows” on transmittion lobes.

Finally: if you want an antenna for any FieldDay, walk on the country, contest, try it! Its my favorite antenna for any mini DX-pedition, IOTA operation arround Greek Islands. It’s just a wire “plus” a balun! Have you any better idea?

Have Fun!

https://www.qsl.net/sv�bsx/windom/windom.html

Our thsnks go to SV1BSX …Mike (Ed)

HARS Journal - FT8

Good Evening Mike,

Regarding the article on FT8. When I started using FT8, like most others were using Dimension 4 for the Network Time Protocol. After 12 months Dimension 4 started to lose the plot with a time error of anything up to �.2 seconds and hence no more FT8 QSO’s.

Digging around on the World Wide Web thingy, a lot of other FT8 operators were having the same problem, some were reporting no user backup from Dimension 4 to correct the problems.

The general consensus was to migrate to the Meinberg system, full details are at https://www.meinbergglobal.com/english/sw/ntp.htm together with the with the downloads for the various operating systems. I changed to Meinberg and all the FT8 problems disappeared - some 2 years ago and no problems since. The last time I checked the time accuracy I was 0.00�2 seconds slow which is accurate enough for our needs!

Keep safe and Best Regards, Dave, G4IDF aka The Chassis Bashing Man!

Thanks, David …Mike

https://www.meinbergglobal.com/english/sw/ntp.htm






copper pipe. As the name implies, it contains an acid that etches the copper to ensure a good joint. Used on electronics, it can damage components and wear out the tip of your iron much faster.

Temperature settings are important when working with delicate components. Too much heat can damage some semiconductors. You want the iron hot enough to get solder flowing properly over the joint, but if it starts melting everything around it, you’ll want to back off on the heat.

Keep the tip clean and in good condition. This is vital. Some tips wear out faster than others, so keep a spare on hand. Most soldering stations have a spot for a damp sponge to wipe excess solder and other residue off the tip. I’ve seen engineers use a kitchen scour pad.

Eye protection when soldering is a must. Molten solder can splash, and flipping a drop into your eye is no way to spend a Saturday night!

Good ventilation is important, too. Remember, the metal alloy in solder can contain lead (especially older solder), and you don’t want to inhale that smoke. A small fan on your bench is helpful. If a fan is not available, at least try not to park your face right above your work. Wash your hands after soldering, so any residue doesn’t end up in your mouth or eyes.

Obviously, burn prevention is the rule. These tools reach about 600–800 degrees Fahrenheit. You definitely want to rest the iron somewhere safe. Soldering stations address this with a dedicated holder. Some irons come with a little folding rest to keep the heating element off the work surface. Personally, I’m not fond of these. A bump or a tug on the cord can send the iron rolling across the bench. Make sure the tip is on tight before you turn it on. I once had a loose tip fly off in the middle of a job. Thankfully, that 800-degree piece of metal didn’t land in my lap, but the burn mark in the rug was there to remind me for years!Hot IronSo now you’ve got your iron hot and your solder ready.

When working on a PCB, make sure the piece is planted firmly so it can’t slide around while

Soldering Tips for Beginners

Learning the basics is smart for any skill or skill levelBy Curt Yengst

Most, if not all, engineers know how to handle a soldering iron. But there are a few folks in the industry who want to know more about those wisps of smoke they sometimes see rising from our workbenches.First Things FirstFirst, you need the right tools for the job. As is often the case, the amount of money you spend can vary greatly. For years, I’ve been using a Radio Shack soldering station that set me back all of $25, and it’s been very reliable. Someday, before I retire, I plan to splurge on a nice $50–60 soldering iron from Weller. I’ve seen some units costing hundreds of dollars.

They all perform the same basic function: get hot enough to melt solder. The better units have some form of temperature control, either a rheostat or a simple two-position switch to determine wattage. On the other end of the scale is your basic soldering iron without the stand or temperature control, which some of us keep in our tool bag.

Next, choose a solder with the right alloy formulation and flux. The most common alloy is 60 percent tin and 40 percent other metals, like silver or antimony. Lead has been commonly used but is being phased out.

Flux is a reducing agent that prevents oxidization and improves the chemical bond between metals. Always use rosin flux solder for electronics, never acid flux. That’s the kind plumbers use to join or “sweat” pieces of


By the way, when working with in-line connectors, make sure to slide the connector’s outer shell on the cable before you solder the connector. Many harsh words have been uttered over the years by engineers who smiled over a fine soldering job only to have to take it apart because they forgot this step!

Speaking of which, occasionally you’ll have to remove soldered components. For this you’ll need a desoldering suction tool or desoldering braid. The braid uses the wick effect to remove solder.

Heat the joint you wish to remove until the hardened solder melts, then place the end of the braid against the tip of the iron. The softened solder should wick out of the joint

and into the braid. The suction tool works by using a spring loaded plunger to create a burst of vacuum pressure to suck the molten solder away.

Sometimes, the old solder joint won’t melt right away. If this happens, introduce some fresh solder as you apply heat. The flux in the fresh solder will help break down the old joint.

As with any skill, good soldering takes practice. If it’s something you’d like to pick up, find an inexpensive iron and start by working on cable connectors. Once you get the hang of it, improve your skills on the connectors. When you’re comfortable, find a small electronic kit with a PCB and try your hand at that.

With practice and experience, you’ll find this a very useful skill to have. Happy soldering!

https://www.radioworld.com/tech-and-gear/soldering-tips-for-beginners

Thanks, Curt …Mike (Ed)

you’re working. A Panavise or similar clamp is handy.

On the trace side of the board, the component leads will protrude through the holes in the traces. Place the tip of the iron at an angle with one side against the lead and the other against the trace. In just a few seconds everything will be hot enough to introduce the solder.

Place the tip of the solder wire on the opposite side of the lead from the tip of the iron. The solder should immediately flow around the joint.

Quickly remove the solder wire. Too much can spread beyond that trace and cause short circuits, or solder bridges to other traces.

The finished joint should look like a nice, little shiny mound of solder. If the joint looks crystalized or cracked, or you can still see the hole, this is an incomplete, or cold, joint. Apply the tip of the iron again for a few seconds to reflow the joint.

After the joint solidifies, clip off the excess wire as closely as possible. If you’re working on IC pads or very tiny components, a finer tip might be necessary.

What about when you are working with connectors or panel-mounted parts?

There are usually solder lugs or pins provided. First, strip the end of the wire just enough to make the connection. An eighth to a quarter of an inch is usually adequate. It helps, especially when working with stranded wire, to heat the exposed wire and apply a bit of solder. This tinning keeps the strands together and makes it easier to bend the wire around a lug or pin.

Putting a small bend in the end of the wire, place it in the lug. Then place the iron tip against the lug, making contact with the wire as well, and introduce the solder. As with the PCB joint, the solder should flow evenly and solidify smoothly.

Be sure to apply heat just long enough to melt the solder, but not the insulation on the wire. On XLR or D-sub connectors, the contact pins usually feature tiny cups on the soldering side. Before creating the joint, it helps to flow a bit of solder into each cup.



Page �0 Issue No 24 • July 2020 H.A.R.S. Journal

Hereford’s First Radio

Amateur

by Bob Bowden G3IXZ

The year �9�4 will no doubt be remembered for evermore mainly because, in July “the War to end all Wars” commenced. However, a few months before this date, a rather special and “signal” (literally) event occurred. Hereford’s first radio amateur obtained his licence from the Postmaster General.

The gentleman in question was Mr Walter Pritchard, a successful tailor and gentleman’s outfitter in the City of Hereford. Like many educated men at that time, he was greatly enthused by the technology and the use of wireless communications, which was rapidly growing in range and efficiency by this time. The general use of wireless equipment by the public was rather frowned upon but the General Post Office had, for some time, permitted applicants who wished to experiment with the technology to apply for a licence to carry this out – initially with receiving equipment only. A copy of the licence obtained by Walter is shown in (Fig 1).

His licence restricted him to reception and in that period of development of wireless receivers this required the use of a crystal detector to provide a source of rectification so that the presence of a distant spark generated radio signal would provide a rectified waveform and the presence of a dots and dashes for reception of morse code messages.

The transmitters would almost certainly have been of the spark variety and consisted of a high voltage spark gap driving a relatively crude tuned LC circuit which provided a very wideband signal covering a many tens of kilohertz and centred in the long wave band between 30 and 300 kHz. The medium wave band was also becoming utilised by this time and frequencies above 1 Mhz would have been experimented with but the ionosphere was a complete mystery and long distance communications was thought to be dependent upon using the lower frequencies.

Fig 1: Walter Pritchard’s first licence

Fig 2: receiving set-up

Walter erected a fairly big antenna – ostensibly a long wire, which he ran from above the back of his shop premises, across Broad Street onto the top of the library roof. With this setup he was able to listen to time signal transmissions from Paris plus international high power services from the Marconi station at Poldhu in Cornwall and also, at about this time, from the huge spark transmitter in N.Wales. His receiving set-up appears in (Fig2) with a slightly upgraded station in( Fig3) This shows his relatively simple receiving station laid out on a table with easy access to the crystal detector – an essential part of most amateur stations at that time. All required the use of morse, of course.there is no mention of requirement to read morse in the licence.

H.A.R.S. Journal Issue No 24 • July 2020 Page ��

His experiments with aerials included some hoisted up by a balloon and another by a large kite which was understood to have nearly brought about his electrocution by from lightening!

Following the outbreak of WW1 the authorities impounded all amateur radio transmiting equipment, which included receivers as well as transmitters. However, it is hard to believe that most licence holders would not have retained a small crystal detector and tuned circuit which, with a simple indoor aerial and headphones would have permitted reception of numerous military and public service transmissions taking place during the war years.

I recently read a paper outlining on the use of wireless in WW1 to communicate with Home Defence aircraft used to combat frequent Zeppelin attacks, which increased as the war progressed. This entailed the use of some 50 radio stations spread across the country, to enable details of attacking enemy aircraft and Zeppelins to be conveyed to patrolling RFC fighter aircraft from various UK bases – during the hours of darkness. Adding these to the high number of wireless service transmissions, already in existence would have

provided the crystal set users with a feast of interesting traffic.

Following the resumption of peacetime operations, the Post Office released impounded equipment and amateur radio operations commenced again. However, the war years had produced a huge change in the available technology. The thermionic valve had developed from the simple diode devised by Ambrose Fleming to the triode tube, invented by the American, Lee De Forest, who had added a grid structure between cathode and anode, to completely change the face of electronics and its applications. Walter Pritchard then applied for and was granted

Fig 3: slightly upgraded station

a transmitting licence, with the callsign 2QO. Walter went on to produce a valve AM speech transmitter and provided speech and music transmissions using AM (Invented by Canadian, Reginald Fessendon �9�8) for the local public to listen to – long before the BBC was brought into being. A picture of the later station is shown in (Fig4)which could have been turned nto an early form of QSL card, showing Walter and his equipment with his callsign written on a board above his equipment.

Fig 4: the later station


ascertain but it seems unlikely. Walter passed away in 1949 and his outfitting business was continued by his son Percy who, I believe, had an equally enquiring mind and a profound interest in transportation methods.

“I would like to thank Elizabeth Patrick and my friend and historian/ photogapher Dr Derek Foxton for providing material for this article’.”

73 Bob G3IXZ

Thanks you Bob …Mike (Ed.)

Walter, meanwhile had pre-war carried out work experimental work with Aviation a subject close to his heart from earlier in his life. He had always been interested in aviation and constructed and flew a small unmanned balloon in the �880s and later in the

Fig 5: small unmanned balloon

Fig 6: Dinmore near Bodenham

�930s constructed a simple training glider, which was launched from a suitable slope at Dinmore near Bodenham. (See Fig 5 and 6) During the pre WW1 years he had travelled to Europe and flown in a balloon in Paris and met some famous early aviators like Hiram Maxim, Wilber Wright and Col Bill Cody,who glamorised the early years of the century – particularly in France. Walter had an excellent workshop to construct his equipment.(Fig 7).

In the early �920’s the legislation associated with amateur wireless operation and in particular the transmission of music and programme material, began to come into force and the BBC claimed a government monopoly on Public Service broadcasting. No doubt many were disappointed by this and Walter was probably disillusioned and surrendered his licence and callsign. The call 2QO was reissued and is later listed in Jack Hum’s (G5UM) callbook of the �920-�939 period. It shows Percy Pritchard, followed by a Mr A. Dearlove, who was located in Hull. And so Hereford’s first radio amateur can be aid to have “hung up his headphones”. Whether this was in fact the case is not now easy to

Fig 7: Walter’s workshop

H.A.R.S. Journal Issue No 24 • July 2020 Page �3

The N7DDC – 100 7x7 ATU

a report by Halisi Drysdale MW7ISI

While waiting for my G5RV to arrive I decided that my research into antennas wasn’t complete without looking at the design of matching units, a decision helped by my lack of a tuner in the first place. With this motivation to build one, I discovered a massive resource of information online including schematics, software for simulating and calculating coils or capacitors for RF. While searching information on transmission lines and antennas, I came across a fun project that can be wound and soldered in a couple of hours or so, leaving you with an automatic tuning unit which clicks away and works on the desk... as an ATU kit it’s an interesting find with practical application.

Oddly, there’s not much on YouTube or the internet about this fantastic little kit outside of the Russian-speaking world, where it seems a very popular unit. I think it deserves a little recognition, as does the designer for making it available open source for us to have a go. Kit detailsN7DDC, David Fainitski, designed this ATU and it’s now on revision 2 with a very compact form (I measured mine to be �20 x 62 x �5 mm with the populated PCB board). It operates up to 100 W limit – for me an ideal range given that as an M7 it allows me to grow into the further licence range while offering a lightweight QRP tuner. The “7x7” kit

The one I ordered from ebay arrived within a couple of days and I set to soldering as soon as time allowed. 7x7 refers to the 7 inductors and capacitors utilised for matching between 1.8 MHz and 50 MHz, but there is a smaller 5x5 version which is a little smaller and allows tuning between 3.5 MHz and 30 MHz. This range is in effect up to the maker as the option to code or program the PIC�6F chip allows any reasonable range of LC, linear or logarithmic, combination. I stuck with the “basic” set-up although my version of the air-wound coils were recalculated (*�) for the same inductance but based around the former I had immediately to hand, which happened to be the stem of a 5 mm HSS drill bit... it was early hours of the morning and I

wasn’t in the mood for heading outside to my workshop for any other size of former. The measured inductances worked well against the calculations using a nanoVNA(*2).Bonus parts!The kit comes with all parts needed including the PIC�6F�938, SSOP28 chip – nearly all parts are SMD so came on cut tape. One nice packaging feature was that the number of passive pieces allowed for �0% spares, so no panic over a dropped resistor. Parts were in sealed bags, grouped by type. Ferrite rings and wire were also in sealed bags; one spare ferrite ring was included along with around �0-20% extra wire as well. In all, a great kit with which to confidently get started. The instructionsWhat you won’t find in the box are any instructions or links of any kind. This is not a negative, it’s the nature of the great design that the board is very well labelled on its silk screen and that up-to-date documentation is available online in the designer’s GitHub page (*3). Schematics and photographs are all included in his master folder so the entirety of this project can be completed from this repository.

Sadly I didn’t think to take any pictures until another amateur mentioned that I should keep a record, so I can’t show the individual items viewed as they arrived, but have a photo taken not long after starting.

Figure 1. The initial PCB after I started populating the board, with some of the components visible at top of photo. (Ignore the random notes behind the board!)


In the confessional!For clarity, I am no expert in electronics, my trade being carpentry and now smallholding but I have dabbled (blindly) with projects and learning in electronics during my teens, and until this day – with that said, apologies as I may be making technical mistakes in some of this writing... I was told that falling is by far the quickest way to learn how to stand back up, so please do correct me. ConstructionAs evidence of falling: this kit went together like a dream armed with only a soldering iron; then I spent twice as long trying to remove the rosin from between the legs of the Vdd and Vss on the PIC�6F chip... something that leads to magic smoke and a gentle reminder that you can make sparks even at 5 V. Anyway, my drag soldering and attention to using the correct flux for SMD flow will make the next project a little less exciting, miniature-fireworks-wise! The 7x7 kit has a very small form factor SSOP28 chip with tiny 0.65 mm leg spacing at centres. If this is a worry then the 5x5 kit uses the larger DIP28 package with much a more manageable spacing of 2.54 mm between centres. I only have a regular soldering iron, no hot air station, but the board is pre-tinned so was able to use drag soldering with lead-free solder for the SSOP chip assisted by flux gel.

I’ve included the pictures of my final device in PCB form, but the finishing touches are awaiting free time, these being a project box with 128x64 OLED display to show the L and C setting, as well as the VSWR and real-time power level. The programming allows for use of several options, the simplest requiring no peripherals and working entirely on auto-mode

with a programmable threshold level. The next option uses three LEDs to show that it’s on or tuning, and show that the VSWR is good/medium/poor. The final option uses of 128x32 matrix LCD or 128x64 OLED display. FunctionalityAll of the functions plus the settings for coils, etc. are saved to the EEPROM of the chip via direct manipulation of the HEX files, but no programming knowledge is needed as the user manual from the GitHub repository gives very clear instructions on adjusting these settings directly in memory. The board is powered by 10-15 VDC at its input, with its linear regulator supplying 5 V to the chip. I tested the input through its range and it drew 0.3-0.4 A with all relays active, and 0.02 A with no relay load, so lightweight enough for 12 V battery powered application. As of writing I have not received the OLED display, but very basic tests saw mine tuning with the recommended minimum 5 W input, with auto-mode activated at a pre-set of 1.3 SWR. Function buttons are activated to ground with a �00 pF capacitor in parallel.

There’s combinations of 7 inductors in series, and 7 capacitors switched to ground in parallel, before or after the inductors, creating an L-match. Based on this, the kit offers (2x(128x128))-1 or 32,767 combinations so its small footprint seems more than capable in principle (Best you double check my maths!).AssistanceIf anyone wants to give this project a go you will need a PIC programmer (*4) to

Figure 2. The finished PCB, here placed in the box that the kit arrived in highlighting the care given to the

product’s postage.Figure 3. The soldered SMD items on the reverse of the board showing the extra B1/2 and A6/7 pins used for

remote control and additional button functions. Details are in the downloadable manual.


flash the chip or set the parameters; I have a programmer and computer software loaded, so can happily pre-flash your chip if needed or helpful. Alternatively, third party versions of the PICkit3 programmer can be found online at reasonable prices. The LED/OLED display pins are used for programming on the board so alterations can be made at any time.Compatible RigsIn addition, the board will also work remotely from ICOM, Yaesu or other transceivers which support triggering external devices – it has both a high or inverted pin pads for connection to a transceiver. ConclusionIn all, N7DDC has created a very neat design (*5), all open source, and shared with the World of Amateur radio, although at the price of this package delivered, ordering the individual parts would be several times more expensive than buying this as a kit – a crazy and wonderful world! I messaged the designer who replied promptly to say he’s currently working on the latest model which will have a full balanced line incorporated on the board... a little time away, but I suspect I’ll be tinkering with the new version when it arrives on the virtual shopping shelves!

A short demonstration video, made by the designer can be found on his YouTube channel, which is only four minutes long so well worth a view. (*6)

Hope this is of interest,

Hal, MW7ISI [email protected]

Notes

*�. Calculations were made with the assistance of Coil32/coil64: https://coil32.net/

*2. Measurements of inductance were made using a nanoVNA.H4: https://owenduffy.net/blog/?p=17298

*3. GitHub for David Fainitski, N7DDC. Source, Hex, schematics and manual: https://github.com/Dfinitski/N7DDC-ATU-�00-mini-and-extended-boards

*4. Microchip’s download archive where support for the PICkit3 programmer can be found. The download is closer to the bottom of the page:

https://www.microchip.com/development-tools/pic-and-dspic-downloads-archive

or the direct link to the PICkit3 stand-alone software:

http://ww�.microchip.com/downloads/en/DeviceDoc/PICkit3%20Programmer%20Application%20v3.10.zip

*5. My ATU was delivered within two days, costing a little under £35. The 128x32 LCD or 128x64 OLED can be found for under £5 to complete the unit, if a screen is wanted. This seemed to be the only kit shipped from the UK, others had a long lead time for delivery. Filter the search by ‘UK only’ and the ATU should still be available:

https://www.ebay.co.uk/itm/Automatic-Antenna-Tuner-7x7-PCB-ATU-100-mini-by-N7DDC

*6 David Fainitski’s (N7DDC) demonstration video, subtitles are available in the options:

https://www.youtube.com/watch?v=zBjliED9-OE

Other resources and learning found online which related in some part to this project:

7. David Knight’s (G3YNH) writing on various electronics and RF subjects; he has his own online inductor calculator and contributed to work on coil32: http://www.g3ynh.info/zdocs/index.html

8. LB Cebik, W4RNL, (now SK) whose various articles can be found on many on-line archives. I doubt this collection is new to anyone but myself, but was a massive help with information on NEC2 modelling as well as articles on transmission lines and matching:

http://on5au.be/content/radio.html

http://on5au.be/Cebik%20documents.html

9. Iacopo Giangrandi is a Swiss electronics engineer who wrote a short piece explaining tandem matches:

https://www.giangrandi.org/electronics/tandemmatch/tandemmatch.shtml

Thank you Hal … Mike (Ed.)

https://coil32.net/

https://owenduffy.net/blog/?p=17298

https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards

https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards



http://ww1.microchip.com/downloads/en/DeviceDoc/PICkit3%20Programmer%20Application%20v3.10.zip








http://www.g3ynh.info/zdocs/index.html

http://www.g3ynh.info/zdocs/index.html

http://on5au.be/content/radio.html

http://on5au.be/Cebik%20documents.html




https://www.ebay.co.uk/itm/QRP-SSB-Transceiver-Taurus-20-KIT-for-assembly-/172486857413?_trksid=p2385738.m4383.l4275.c10

QRP SSB Transceiver «Taurus-20». KIT for assembly




Printer

Items for sale.

OFFERS? Mike G3LZM (01432 272987)

Two Cases

SX600 antenna meter

Telephone

Spectrum Analyser 26.5GHz Advantest R3271

6GHz VNA HP8657B

Solder station with iron and restTwin variable PSU with 5V


Mercia Radio TelephonesUnit1.GrandstandBusinessCentreFaradayRoad‑Hereford‑HR49NS

Tel: 01432 267864Calling all radio hams…!

Icom equipment for you!

Call Stuart G3WRA now for that special, special, deal.

Articles Wanted!

Please think about submissions/projects you might like to send in or see.

General topics and key words are listed below.

Members projects Members station Construction Items wanted Items for sale Hints and kinks

Events Notices Help News DX Militaria

Training QRP/QRO Illustrations Photographs Early radio Restoration...

... or anything else that you think might be of interest to HARS members. If you have an idea for a submission, but don’t know how to present it, I will do it for you.

Please submit anything and everything to [email protected] or talk with Mike at the Club meetings.

73s es GDX, G3LZM Mike Bush (Editor)

HARS radio equipment available

for loan to Club members or for

purchase

The following list of equipment is available for loan to Club members. The loan period is 3 months and members wishing to use the equipment will have to sign a simple agreement which covers the loan terms. If you wish to borrow then please contact Duncan (Hon Sec) M0OTG.

Grid Dip Meter MFJ-201Buddipole �0-40M portable antenna with tripod and carrying case.Yaesu FT450 All bands to 50MHz. Needs a 12V PSUPixie 7MHz QRP kit. Needs assembling.Baofeng UV-5R 70cms/144MHz hand-held complete with accessories.

Go portable with the Buddipole! Ed.

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The HARS Technical Library

This is the new lending library thanks to Bob G3IXZ, who is the “owner”. The library is of course at Hill House - thanks to Geoff G8BPN. Great stuff here…, do take a look.

Subjects covered include: Antennas, Technical, Reference, Historical, Equipment and QRP.

This is really good Bob…thanks …Ed.


HARS Club Nets etc.

by G4XTF

Hi Folks,

I don’t know about you but I am now getting a serious bout of cabin fever. Eight plus weeks of lock down and I have not really been out “out” all of that time. In fact one of the cars has stood for so long that the brakes need freeing off.! However, I have been in contact with many of the members of HARS. The use of the club nets have grown, especially G3YDD the Saturday net on 3.770MHz. Which is fine if you have a garden big enough for a reasonable 80 metre aerial. If not, what can one do to be able to talk to one’s friends?

For some considerable time David M0RNI had been on to me to use my FT1D on the internet through a “top hat”. MMDVM a system that can be used with Pi-star and allows one to operate C4FM…, in to the internet and through various nodes and rooms and out to the world. Yes, it is possible to talk to somebody in a Big Mac going down the route 66 using a few milliwatts. Maybe the driver is a ham called Burger!

To be honest I do not really understand how it all operates but like driving a car you do not need to know about the engine and gearbox. However, you do need some software called Pi-star.

Pi-Star is a great software package for digital voice hotspots and repeaters. It can handle DMR, D-STAR, and YSF, and even P25, NXDN, and YSF/DMR cross modes when used with a multi-mode digital voice modem that supports those modes.” (Quote copied from Google)

What do you need?A Yeasu UHF transceiver capable of C4FM. (Other rigs and modes are available).A Raspberry-pi that has WIFI or one of the newer Pi Zeros.A MMDVM top hat for the Pi (Ebay )Pi-star softwareA good viewing of one of the “you-tube” programs on setting up Pi-star.

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Come and join us. Dave M0RNI, Richard 2E0JRS, Stewart G4VMF and myself G4XTF on FCS00415 any Sunday and Wednesday mornings.

If this does not float your boat there are many ways of passing the hours. Have you tried SSTV? That is sending pictures by radio. How about learning the simplest digital form of transmitting i.e. C.W. Whatever you do, now is the opportunity to become more “time involved” in this fascinating hobby and not feel guilty.

I look forward to hearing you on one of the following nets.

Saturday 0930hrs 3.770MHz +/- LSB HARS net G3YDDSunday 1030hrs 3.770MHz +/- LSB A net run by G3NDM and welcomes all comers.Sunday 1000hrs 70.475MHz FM Give it a call…, Tends to be monitored by M0RNI, 2E0JRS, G4XTF.Sunday �000hrs Fusion net on FSC004�5Tuesday 1030hrs 3.770Mhz+/- LSB As Sunday G3NDMWednesday 1000hrs 70.475Mhz Give it a callWednesday 1000hrs Fusion net on FCS004�5Wednesday 2000hrs HARS net on GB3VM repeaterThursday 1700hrs 144.040MHz C.W. Followed by a chat on 145.375Mhz FM

Thanks, Nigel … Mike (Ed.)

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h.a.r.s. journal · came into place. there are currently about 75,000 licensed users in the uk....

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